Introduction: Essential Thrombocytemia (ET) is a clonal stem cell disease that manifests itself with proliferation in the megakaryocytic lineage in the bone marrow, with clinical presentations ranging from asymptomatic to bleeding and thrombosis spectrum.
In medical treatment, aspirin and/or monitoring are recommended for low-risk patients, while cytoreductive therapy is recommended for high-risk patients. Cytoreductive therapy is often used in patients with a very high platelet count (>1,000,000). The first choice in cytoreductive treatment is Hydroxyurea, and Anagrelid treatment is preferred in the young patient group and patients with hydroxyurea resistance/intolerance.
This study aimed to evaluate the effects of the JAK2 mutation, which is associated with high risk, in the patient group receiving anagrelide therapy.
Method: The files of patients diagnosed with ET according to 2016 WHO criteria and followed up under Anagrelide therapy in our center between January 2002 and December 2021 were reviewed retrospectively. In addition to the demographic data of the patients, diagnostic tests, bone marrow evaluations, JAK2 mutation status, and laboratory data were noted. Patients were divided into two groups according to JAK2 mutation positivity and negativity. The obtained data were compared between the two groups.
Results: Thirty-three patients (male/female: 20/13) treated with Anagrelide for the diagnosis of ET were included in the study. It was observed that 14 (42%) of the patients were positive for JAK2 mutation. There was no significant difference between the groups regarding age at diagnosis, gender, duration of anagrelide use, and bone marrow fibrosis degrees. When the laboratory tests were compared at the time of diagnosis, the WBC count was significantly higher in the JAK2 positive group; other series were similar. When the last control laboratory data of the patients were compared, WBC, neutrophil, and hemoglobin levels were observed to be significantly higher in JAK2 positive patients, while LDH levels were significantly lower.
Conclusion: It was observed that JAK2 mutation positivity, which is associated with high risk in ET risk staging, did not negatively affect anagrelide treatment response. In ET patients, leukocytosis (>11,000/mm3) has been identified as a risk factor for the whole lifespan. It was observed that the WBC counts of the patients who were positive for JAK2 were significantly higher at the time of diagnosis and during the treatment process. Since the LDH level after treatment is higher in patients with positive JAK2 mutation, it has been evaluated that JAK2 mutation may play a role in resistance to cytoreductive therapy.